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Thursday, 14 February 2013

Using Regulatory Immune Cells to Control Arthritis

For years now immunologists have been trying to understand auto-immune diseases, which occur when the immune system turns its weapons on the cells of its own body. This is no easy task because the immune system is extremely complex, consisting of many different types of immune cells and a host of complex chemicals. All of these interact and like the musicians in an orchestra they normally they produce a seamless performance. Orchestras need to play faster and more loudly at times but they also need to reverse this so as to play softly or slowly. In an autoimmune disease it’s as if one section of the orchestra is ignoring the conductor and just keeps playing louder and faster. The conductor’s job in the immune system is undertaken by regulatory T cells. These are a type of lymphocyte, also known as Tregs or CD8 cells, that calm things down after a period of inflammation. 
One of the most common autoimmune diseases is rheumatoid arthritis. In arthritis immune cells start attacking joints and the inflammation this causes runs out of control. For some reason the Tregs can't calm things down.
In some recently reported work, researchers injected some of Tregs into mice with arthritis and they worked – reducing the unwanted inflammation in the joints. They also used a technique to increase the number of Tregs produced by the mice and this also worked.
It is no easy task to tweak the workings of the immune system. Conventional drugs such as steroids can blunt more than one aspect of the immune system and cause other serious side effects throughout the body.
Experiments like these are beginning to give hope that one day the mountain of research papers in immunology will pay some real dividends in terms of treatments.

Friday, 8 February 2013

Immune System Even Cleverer Than We Thought

In any branch of science there are moments when conventional wisdom is overturned. One of those moments has just occurred in immunology as a result of research at Stanford University. Our previous understanding was too simplistic. Things are even more complicated than we thought.
For years now everyone has believed that lymphocytes can learn to recognise specific molecules but that each type of lymphocyte can only learn a single lesson. One kind of lymphocyte can learn to recognise measles virus, another can learn to spot whooping cough bacterium on sight and another can only be activated by a particular protein made by prawns. Once a lymphocyte has had its initial exposure it will produce memory lymphocytes (CD4 cells) that will hang around for the rest of your life, waiting patiently to deal with a second encounter. This is how adaptive immunity and, of course, vaccination works. 
But the one lymphocyte = one lesson theory has just been blown out of the water. It seems that lymphocytes can generalise their learning.
The human brain can generalise easily. Learner drivers are taught to negotiate road junctions. Once the basic skill is there, they will be able tackle all kinds of road junctions. No two junctions are identical but nevertheless the competent driver tackles them all confidently. The learning has been generalised.
Now it seems that memory lymphocytes have some ability to do the same kind of thing. They are even cleverer than we thought. They can recognise not only the microbe that first activated them, but some other types as well.
We knew the immune system was magnificently complicated and now we have to acknowledge the existence of a whole new level of complexity. This new knowledge may shine a light several aspects of how the immune system learns about its environment, such as how benign bacteria help the immune system to develop in childhood.